Pancreatic cancer is the uncontrolled growth of abnormal cells in the pancreas. The cancerous cells form malignant tumors, which damage tissue, keep the pancreas from working the way it should, and may eventually spread (metastasize) to nearby or distant organs and tissues.
The pancreas is a narrow, flat gland about six inches long located deep in your abdominal cavity, behind the stomach and below the liver. It has head, body, and tail sections. Its head section connects to the first part of the small intestine (duodenum).
- Inside the pancreas, small ducts (tubes) feed digestive enzymes and bicarbonate produced by the pancreas into the pancreatic duct. This large duct carries these down the length of the pancreas, from the tail to the head section, and into the duodenum.
- The common bile duct also usually runs through the head section of the pancreas, carrying bile from the liver and gallbladder into the small intestine.
- The bile duct and pancreatic duct usually join just before entering the duodenum and share a common opening into the small intestine.
The pancreas consists of two kinds of tissues that perform different functions:
- The exocrine pancreas makes, stores, and releases powerful enzymes to digest fats, proteins, and carbohydrates in the small intestine. Some of the enzymes are produced and carried in an inactive form to the small intestine, where the enzymes are activated as needed. Exocrine tissues also make and release bicarbonate that neutralizes stomach acids and allows for the activation of pancreatic enzymes.
- The endocrine pancreas produces hormones, including insulin and glucagon, and releases them into the blood. These hormones regulate sugar (glucose) transport into the body's cells, where it is used for energy and to help maintain normal blood sugar levels.
Most pancreatic cancers (about 95%) begin in the cells that make up exocrine tissues. These cancers are hard to detect at an early stage because symptoms are usually subtle or absent and tumors cannot usually be seen or felt during a physical exam. By the time symptoms such as jaundice occur, the cancer has often spread throughout the pancreas and beyond.
Cancer can also begin in the pancreatic cells that make hormones, which are called neuroendocrine cells. Neuroendocrine tumors, also known as islet cell tumors, are more rare than exocrine tumors.
- Most islet cell tumors are noncancerous (benign) and do not spread. Those that are cancerous (malignant) tend to grow and spread more slowly than exocrine tumors.
- Islet cell tumors can be detected earlier than exocrine cancers because they can cause signs and symptoms if they produce excess pancreatic hormones, such as insulin or glucagon. Simple tests may be used to measure levels of these hormones in the blood to determine if they are elevated.
Exocrine tumors (e.g., pancreatic ductal adenocarcinoma) will be the focus of the rest of this article because they are more common than islet cell tumors.
Pancreatic cancer is the fourth leading cause of cancer death in men and women in the United States. According to the American Cancer Society, nearly 57,000 Americans are diagnosed with pancreatic cancer each year, and about 46,000 die from it. It is slightly more common in men than women.
